Circuit Description

When power enrichment is requested from PCM, the PCM monitors HO2S reading to ensure power enrichment (heavy acceleration) has been achieved. If during power enrichment, rich exhaust is not detected by the PCM, DTC 1171 will set.

Conditions required to set DTC are:

• No related DTCs are set.
• Engine is operating in closed loop.
• ECT is greater than 140°F (60°C).
• HO2S voltage remains less than .4 volt for 3 seconds while in power enrichment mode.